This invention relates to an anti-friction device for use under hostile conditions, such as in high temperature or high nuclear radiation environments, or under sustained impact loading.
The use of a fabricated polymeric material for an anti-friction device, (commonly called a bearing) has recently become known, as shown by U.S. Pat. No. 3,711,166, to Wayson. In this patent, a fabricated sheet of TFE-fluorocarbon fibers by the du Pont Company (sold under the trademark "Teflon") or other material of similar characteristics is used as an element in an anti-friction device to reduce the coefficient of sliding or rolling friction at a surface between two structural members. This device is used where relatively heavy load bearing members must be permitted to move relative to one another. For example, in a bridge or a hydroelectric power generator, the members of the structure develop considerable stresses through temperature and weather variations and the application of dead and live loads. To relieve these member stresses, bearings are positioned at strategic positions between the members. These bearings allow the members to move relative to one another at low speeds due to the relatively low coefficient of sliding or rolling friction at a surface, thereby relieving stresses.
While the anti-friction device of U.S. Pat. No. 3,711,166 has been found to perform excellently for its intended purpose, its use for certain other applications has been limited. Thus, where the anti-friction device is exposed to high temperatures or to high levels of nuclear radiation or to sustained impact loading or some combination of these, degradation of the material of the device will have adverse effects on its anti-friction properties.
Similarly, if other known bearings are exposed to these hostile environments or loading conditions, they will be destroyed by this exposure. Some examples of these special applications where such hostile conditions exist are as follows: between electrostatic precipitators and their supports; between condensors and their supports; between pipes and structural components and their supports in nuclear power installations and other hostile environments; in structures in marine environments; in couplings between a truck cab and its rig, or between subway cars, or other uses where sustained impact loads are applied; and, between a piston and its surrounding cylinder in a high temperature or nuclear radiation environment. Thus, a need exists for an anti-friction device which is capable of withstanding hostile environments or loading conditions.